This first picture, to the right, is my beloved waterproof iPod Nano case. You will note that there is no Nano inside.
This second picture is of my Nano, inside a plastic bag with some rice (because that's what you try to do to save a Nano after you forget to close your waterproof case and don't notice that it's open and your Nano is floating in chlorine water until 20 minutes into your pool-run.)
[and no, the rice didn't work]
Fortunately, I have a "no questions asked" 2 year replacement warranty on the Nano. Unfortunately, Apple's since come out with a new generation Nano, with a different shape that won't fit my case. So, I need to order a new case. In the meantime...
Here are the components of my "poor woman's waterproof iPod" -- a swim cap, a plastic baggie (preferably with one of those zipper seal enclosures), and a iPod shuffle (smallest capacity, so it's cheap).
You take the shuffle, place it in the baggie, and zip the baggie as shut as you can (it won't be perfect, since the cord protrudes).
Then you fold up the baggie, being careful to fold the plastic behind the Shuffle (so you can still press the controls through the plastic.
And then you place the whole thing in your swim cap (again with the control side facing outward, so you can operate it through your swim cap), and place the swim cap-with Shuffle combo on your head. Do NOT look in the mirror - you won't like what you see.
Yes. You look like a conehead. But recall the central tenet of pool-running -- you sacrifice dignity for fitness. This is simply one more aspect of that. And having music in the pool is worth it.
[disclaimer: I am certain that I am not the first to do this, and I believe I've read references to using a plastic bag to waterproof an iPod before. Heck, if you Google it, you'll probably find a better way to do it. But this has worked for me.]